One of the problems facing those maintaining cooking establishments, such as the restaurant and fast food businesses, is the accumulation of grease and oil in the ducts leading from the cooking vent hoods to the air exhaust on the roof. As the air is drawn from the cooking services up through this duct, it deposits grease and oil accumulations on the duct walls. Through time, this buildup becomes both a fire and a health hazard. Further, a percentage of these ducts will not be completely sealed, creating the risk that a portion of the gasses and grease escapes into the attic area creating hazards.
To address this problem, restaurants regularly have a contractor clean the ducts. The current procedure, which must be carried out after business hours, requires the contractor to first cover the kitchen area with plastic sheeting. A funnel of plastic is created to carry soap, water and grease into a container or directly into the floor drains. After protecting the kitchen area, the contractor moves to the roof where a hot water high pressure washer outlet is brought up. The fans are removed which exposes the duct. Generally, excess grease is scraped off the duct as far down as can be reached and is allowed to fall into the plastic in the kitchen area. The next step is to wash the ducts with the high pressure washer and soap. There is a limit to how far down into the duct this aspect of the cleaning procedure can actually reach. Normally a greasy residue is left, especially in the longer ducts. In ducts which are not completely sealed, this procedure can also force water, soap and grease into the attic area. After washing out the duct, the contractor replaces the fan.
In the process of cleaning, the contractor has moved around on the roof for a period in order to properly wash the duct and will generally soak the roof area with chemicals and water. It is reported that this area is the source for most roof leaks in these establishments.
The contractor lastly moves to the kitchen where there is a container of water, chemicals and grease for disposal. This has to be disposed of into the floor drain, grease trap or garbage container. At times leaks develop in the plastic which can cause the water, chemicals and grease to splatter on the cooking surfaces, floors and walls.
In summary, this is a very nasty and time consuming job. Existing procedures require hours of after-hour employee time. In fact, the existing procedures for maintaining ducts are sufficiently disagreeable that restaurant owners delay the process, collecting excessive grease in the ducts and creating a fire hazard, a health hazard and noxious odors. It is an object of the present invention to solve the above problems.
U.S. Pat. No. 4,306,491 to Beaudoin appreciates the above problems and proposes a solution. Beaudoin proposes utilizing a replaceable, expandable elongated metal foil duct liner bag. These bags have balloon walls and are expanded by air pressure, in theory, to seal against the duct. It has been found in practice, however, that these bags are impractical. They develop leaks, and thus do not protect the duct, and/or they become extremely difficult to remove.